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We present evidence from neutron diffraction measurements and molecular dynamics (MD) simulations of three different monolayer phases of the intermediate-length alkanes tetracosane (n-C24H50 denoted as C24) and dotriacontane (n-C32H66 denoted as C32) adsorbed on a graphite basal-plane surface. Our measurements indicate that the two monolayer films differ principally in the transition temperatures between phases. At the lowest temperatures, both C24 and C32 form a crystalline monolayer phase with a rectangular-centered (RC) structure. The two sublattices of the RC structure each consists of parallel rows of molecules in their all-trans conformation aligned with their long axis parallel to the surface and forming so-called lamellas of width approximately equal to the all-trans length of the molecule. The RC structure is uniaxially commensurate with the graphite surface in its [110] direction such that the distance between molecular rows in a lamella is 4.26 Å=3ag, where ag=2.46 Å is the lattice constant of the graphite basal plane. Molecules in adjacent rows of a lamella alternate in orientation between the carbon skeletal plane being parallel and perpendicular to the graphite surface. Upon heating, the crystalline monolayers transform to a “smectic” phase in which the inter-row spacing within a lamella expands by ∼10% and the molecules are predominantly oriented with the carbon skeletal plane parallel to the graphite surface. In the smectic phase, the MD simulations show evidence of broadening of the lamella boundaries as a result of molecules diffusing parallel to their long axis. At still higher temperatures, they indicate that the introduction of gauche defects into the alkane chains drives a melting transition to a monolayer fluid phase as reported previously. [ABSTRACT FROM AUTHOR]

Weiss G, Meyer F, Matthies B, et al. Br J Nutr 2002;87:S89-S94. It has been increasingly reported that administration of n-3 fatty acids is beneficial in patients with inflammatory processes. [...]

High-resolution ellipsometry and neutron diffraction measurements have been used to investigate the structure, growth, and wetting behavior of fluid pentane (n-C(5)H(12)) films adsorbed on graphite substrates. We present isotherms of the thickness of pentane films adsorbed on the basal-plane surfaces of a pyrolytic graphite substrate as a function of the vapor pressure. These isotherms are measured ellipsometrically for temperatures between 130 and 190 K. We also describe neutron diffraction measurements in the temperature range 11-140 K on a deuterated pentane (n-C(5)D(12)) monolayer adsorbed on an exfoliated graphite substrate. Below a temperature of 99 K, the diffraction patterns are consistent with a rectangular centered structure. Above the pentane triple point at 143.5 K, the ellipsometric measurements indicate layer-by-layer adsorption of at least seven fluid pentane layers, each having the same optical thickness. Analysis of the neutron diffraction pattern of a pentane monolayer at a temperature of 130 K is consistent with small clusters having a rectangular-centered structure and an area per molecule of approximately 37 A(2) in coexistence with a fluid monolayer phase. Assuming values of the polarizability tensor from the literature and that the monolayer fluid has the same areal density as that inferred for the coexisting clusters, we calculate an optical thickness of the fluid pentane layers in reasonable agreement with that measured by ellipsometry. We discuss how these results support the previously proposed "footprint reduction" mechanism of alkane monolayer melting. In the hypercritical regime, we show that the layering behavior is consistent with the two-dimensional Ising model and determine the critical temperatures for layers n = 2-5.

Objectives: To determine the efficacy of methylphenidate in improving attention and functional outcome in acutely brain-injured adults., Design: Prospective multiple baseline design (A-A-B-A) utilized on a consecutive sample of patients., Setting: Acute brain injury rehabilitation unit in a large academic medical center., Patients: Eleven acutely brain-injured adults were included by performing below two standard deviations of the age equivalent norms on 4 of 5 neuropsychological tests for attentional capacity. One subject was withdrawn after developing tachycardia., Intervention: After a 1-week baseline assessment, subjects were placed on increasing doses of methylphenidate (Ritalin) so that on Day 7 all patients received a dose of 15 mg at 8 am and 12 pm., Main Outcome Measures: Nine neuropsychological subtests measured attention on admission, at 1 week, while on methylphenidate, and 1 week after its discontinuation. Functional outcome was evaluated utilizing the Disability Rating Scale (DRS) at the same intervals., Results: Digit Span, Mental Control, and Symbol Search scores improved significantly (p < .05) on methylphenidate (A-B) as compared with the pre-methylphenidate (A-A) period. This advantage remained when the drug was removed. The mean improvement in DRS scores on methylphenidate approached a significant difference (p < .06) from that change in the DRS scores between baseline 1 and 2., Conclusions: Use of methylphenidate in acutely brain-injured adults was well tolerated and demonstrated a significant improvement in attention compared to natural recovery in a rehabilitation setting. Methylphenidate also correlated with faster functional recovery as measured by the Disability Rating Scale although the improvement did not achieve statistical significance.

Partially decorticated rats were tested for their response to nociceptive stimulation in the formalin and tail flick tests, and for the effect of morphine on these responses and on motor activity. Undrugged rats showed vigorous responses to nociceptive stimulation in both tests, and exhibited the typical biphasic time course of pain in the formalin test. Morphine 4 and 8 mg/kg produced dose-dependent analgesia in both tests in sham operated rats, and in rats with lesions that removed all or part of the cortex from the midline to the rhinal fissure (excluding the occipital cortex). In rats with lesions that extended deep into the piriform cortex and damaged the amygdala morphine analgesia was eliminated or attenuated. These and other recent findings suggest that analgesia in the formalin test depends on ascending connections to the forebrain, probably the amygdala.

This paper outlines general management strategies used to prevent and control agitation throughout the continuum of recovery from traumatic brain injury. These include environmental management, alterations in the behavior of staff and family, use of physical and chemical restraints, redirection and substitution, time out, operant procedures, self monitoring and relaxation training. The need for both flexibility in choice of strategies and consistency in application is emphasized, along with the importance of staff training and patient and family participation.